An indirect metaphor is a figure of speech in which the comparison of two objects is implied instead of stated. An example of an indirect metaphor is "time goes by," because the relationship between time and a moving object is implied.
According to an article written by Anke Beger, a PhD student and lecturer, the two objects of comparison in a direct metaphor are directly compared in the language of the metaphor, while the two objects of comparison in an indirect metaphor are not directly compared in the language. Rather, readers must infer the comparison into the metaphor from their own experiences.
There are several types of indirect metaphors, including submerged metaphors, implicit metaphors and unstated metaphors. In all these types, a part or a whole of the metaphor is implied rather than stated, making the comparison not obvious.
Metaphors have two parts: a tenor and a vehicle. Both these objects are compared by the tenor borrowing characteristics of the vehicle. In the example "life is theater," the tenor, which is life, borrows characteristics from the vehicle, which is theater, such as drama and action.
Other common types of metaphors include extended metaphors, mixed metaphors, synecdoches, complex metaphors, compound metaphors, simple metaphors and root metaphors.